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tait-rd gime @sind @Mira Letters Patent No. 90,195, dated May 18, 1869.

IMPRovmmNT IN H'oLLow AUGER The Schedule referred to in these LettenPatent and making part of the lame,

To all lwhom. it may concern.-

Be it known that I, H. J. Bronnen, oi' the city oi' Rochester, in theState of New York, have invented a new and useful Hollow 'Ienoning-Bit;and I do hereby declare that the following is a full, clear, and exactdescription thereof, reference being had to the accompanying drawing,making part of this specification, in which- Figure 1 is sideelevation,'with a portion of the head a: cut away, to show' thearrangement of screws h and pins y.

Figure 2 is an inverted view of the face of cutterheads.

The nature of this invention consists in arranging the several partscomposing the expansive cutterheads, in the manner hereinafterdescribed.

To enable others skilled in the art to make and use my invention, I willdescribe its construction and operation.

The shank of this auger is made as others ot' this class, and 'can beused in a carpenters brace.

The head a: is provided with a groove in its edges to receivetransversely-moving arms a.

These arms have T-shaped heads, b, which have on their inner edgescircular recesses, which, when the heads are together, form an openingas large as the smallest tenon required.

rlhe face of the T-heads is slightly convex, so that the knives willmake their cut as other hollow bits.

A cavity is formed in the face of each T, to receive the cutter-knivesj, tig. 2.

This cavity is inclined from the centre of the head to the outside, sothat the knives will be in an inclined position as to the face, so thatthe cutting-edge will be presented to the wood.

The knives are attached to theheads by the screws g passing throughcounter-sunk slots, iig. 2.

At the cutting-edge of the knives f, proper throats are provided in theT-heads, to allow for the passage of chips.

These knives f may be insertedv in slots in the edge of the T-heads.

The arms a are held in the grooves of the heads by means of theright-and-left screws h, iig. 1, and are operated thereby.

These screws hare formed by passing a rod through the head, and makingon its ends a right-and-le'l thread. f

In the centre, ya. groove is cut, and a pin, w, is put through the head,and passes through the groove, and allows the rod to turn, but prevent-send movement. I also, in rear ofthe screw h, insert and fix rigidlyguidepins y, which serve to sustain the arms.

In the edge of the ends of theT-heads, I make a square groove, and littherein a sustaining-bar, p, lig.

1, one end of which is rigidly fastened .to eachT by a screw, and theother end has a slotted hole in it, throilrgh which a clamping-screw,x2, is inserted into the @By this arrangement, when the arms are set atthe desired distance apart by the screw h, the sustainingbars p arefastened by the clamping-screws :and'snstain the heads of the arms a inposition.

On one or both .arms a graduated scale or a movable set may be made toindicate the length ofthe tenon.

The object of this invention is to make an adjustable hollow tenen-bit,so that small as well as large tenons may be cut with the same.

Another object is, lthis hollow bit can be used with 'l any commonboxing-bit, whereas, with the common hollow auger, it is necessary tohave the boring-bit made to t.

This is accomplished in this auger by having the knives adjustable, thatbeing done by turning .the screw h, which will cause them to approach orrecede, as desired, and ,make a tenon to {it any-sized boringbit. Twoscrews may be put in the bars p, to hold the tenon while being out;

What I claim as my invention, and desire to secure by Letters Patent, is

1. The head a, screws h, in combination with the movable T-headed armsa, all being constructed and arranged to operate substantially as andfor the purpose set forth.

2. In combination with the above, the sustainingbars p andclamping-screws x2, as and for the purpose set forth.`

)ELl J. RIOKARD. Witnesses:

Jas. LonENzo GAGE, J. Cruise.

